Fuel injecting device



Oct. 12, 1937. H. POKORNEY 2,095,889

FUEL INJBCTING DEVICE Filed Aug. 5, 1955 6 ,IHVENTUR I Hen/y Po/fomey WITNESS BY v ATTORNEY Patented a. 1 2.1937

UNITED (STATES PATE'N rum. ntrnc'rmc nnvrch- Henry Pokorney, Itome, N. I. u Application Augusta '1935, serial No'. 34,617

Thisinvention relates to a new and improved fuel injecting device for oil-buming internal com: bustion engines of the Diesel t I One of the major problems in the construction of oil-burning-engines of the'Diesel type is the design of a simple, emcie'nt and trouble-free fuel 1 injecting system. The systems heretofore in use may be classifiedas those employing a differential needle valve actuated by the. fuel oil under high pressure,. those in which the fuel oil charge is injected into an auxiliary chamber and discharged therefrom into the main combustion chamber bya preliminary explosion,,and those in which the charge is injected into the combus-- tion chamber by livered froman external source.

The major objection to the difi'erential needl valve system is that the fuel oil must be delivered .at extremely high pressures, from 1200 to 1500 pounds per square inch, which causes frequent leakage of the fuel line at the .points of connectionwith the fuel pump and the injector valve. Also, regardless of the high degree of accuracy to which theinjector needle and the needle a blast of compressed air de-' valve seateZre ground, the injector is never face from an after-drip resulting in,

inefllcient operation andithe formation of carbon.

The second named system in which fuel'oil in jection is accomplished by a preliminary explolyincreases the weight and cost of the engine and practically limits its use a? stationary enzines.

The principal object of my'invention is the provision of a fuel injecting device for oil-buming engines of the Diesel type which eliminates or overcomes many of the objections to and the defects of the fuel injecting systems of the prior art. 7 r

Another object of the invention is the provision of a fuel injecting device having a high degree of flexibility which renders it universally apbustion engines. p v

A further object of the invention is the provision of a fuel injecting device for oil burn'ing plicable to all' types of oil-burning internal com 1 the cylinder head |,'enables the shoulder I 9 to Q be clamped tightly against thegasket' il thus' engines which is simple in construction yet pro-- duces complete combustion. and practically no j carbon.

shoulder 19'. v

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A still further mat of the invention isthe provision of a fuel-injecting device for oil-burn-; ing engines which is operative from a low pres-' sure'sourceof fuel supply.

' Other'objects and advantages relate to the con-"- 5 struction and arrangement of the various ele- -mentsof the fuel injection system and will ap- 1 pear more fully :in the following description taken in oonnectionwiththe accompanyingdrawlng which: I f "1 I Figure 1 is a vertical'fragmentarysection taken through the upper portion of a four-cycle engine showing an embodiment ofmyinventibn; and

Figure 2 is anenlarged vertical fragmentary section taken through the conical {tip of the fuel i injector showing thedisposition of the fuel pas-" sages :oommunicating from the injebtor cylinder to the combustion chamber." In the drawing, the reference. character I designates the upperportion of anerngine cylinder 20 having a reciprocating piston, 6 and a'cylinder' head 1. The cylinder head 'Ihas an exhaust valve ,8 and an air inlet valve 9,'which" valves:1iiaybe actuated by conventional means notshown. I nasmuch as the valveactuating'mechanism-is well known in the art, it is not deemed necessary to" further illustrate or describe thesame. The-cylinder head I- has a substantially central bore IQ for the recsption of a fuel injector ll. .The fuel injector ll comprises a cylindrical body member I2 having a plunger l3 operable in acentral bore l4. The lower end of the body member 12 hasa threaded portion I5 of reduced diameter 'upon which is screw-threaded a conical cup member'- IB which substantially closes the lower end of the bore H to form 'a fuel chamber -I'| below the plunger I3. The cup member l6 has a cylindrical portign 18 of somewhat lessrdiameter than the injector cylinder l2 soas to form an annular The lower endof the 'bore i0 is provided with an inwardly projecting flange 20 .which forms a bore for the reception of the cylindrical portion.

I 8 of the'cupjli. The shoulderv lil'is ad'aptedjto .be'seated'upon agasket 2| carried by the .upper surface of the flangelll. The injector l2 Qlso'has an integrally formed flange ez mcn, in. conjunction with a suitable. numberj of. bolts 7 23 passing through the flange and secured'into hermetically sealing the injector into the cylinder head. 'V

Fuel oil for the operation of the'engine is conducted from .a suitable tankor reservoir, not ifi shown, through a conduit 50 to a low pressure metering pump i of conventional design. The pump 5| is actuated by a'shaft 52 driven in timed relation with respect to the crankshaft of the engine. Inasmuch as driving means for metering pumps are well known in the art, it is deemed suflicient for a clear understanding of the invention to illustrate the same schematically in Figure l by means ofa dotted line 53 connecting the pump shaft 52 with'a rotating cam 46, the operation of which will appear more fully hereinafter.

From the pump 5! metered charges of fuel oil are periodically conducted through a conduit24 coupled to the flange 22 in registration with a passage 25 which, in turn, communicates with a passage 26 in the wall of the injector cylinder l2. The lower end of passage 26 communicates with a bore 21 of greater diameter and extending to the lower end of the cylinder I2. The bore 21 communicates with the fuel chamber l1 by means of a passage 28.

In order to insure a uniform predetermined quantity of fuel oil being injected each time into chamber l1, the diameter of passage 28 is substantially equal to or slightly greater than that of the passage 26 so that the fuel oil will readily'pass therethrough from :the bore 21 into the fuel chamber l1 upon each delivery operation of the pump 5| without causing any appreciable amount of back pressure in bore 21. It is thusseen that the full charge of the fuel oil delivered by pump 5| will! be deposited into chamber l1 during. each discharge stroke or period of operation of said pump. Furthermore, the diameters of the fuel chamber l1 and plunger ii are preferably as shown somewhat greater than that of the diameter of the outlet end of passage 28 so that said passage may be readily closed by the plunger at the end of the entrance of the metered charge of fuel oil into chamber I1 to prevent any additional amount of fuel oil entering said chamber which may be stored in the bore 21 after the end of each discharge stroke of the pump. .J/

In order to prevent the reverse flow of fuel oil through the passage 26, the lower end of this passage is sealedby means'of a ball check valve 28 maintained in its operative position by a coil spring 38. The tension of the spring 88 against the ball 28 may be varied by a threaded plug 8| screw-threaded into the lower end of the bore 21.

The lower portion of the plunger l5 has 'a.

conical configuration and is of the same contour as the conical portion of the cup l6 at the bottom of the fuel *chamber l1. The cup l6 has a constricted central opening 82 communicating with the combustion chamber 33 of the engine cylinder and has a plurality of, in this instance, four passages -84 of smaller diameter radiating ontwardly from the central passage 32, as shown more clearly; in Figure 2. The capacity of chamber I1 is preferably from 8 to 9 times the volume of a single charge of fuel oil injected therein by pump 5| so that only a relatively small portion of said chamber is occupied by each charge of oil while the size 'of opening 32 is such, being only about .007 of an inch in diameter, that the fuel oil will not readily flow therethrough except under pressure. It is thus seen that any fuel .oil which has entered the chamber 11 through the passage 28 will be forced through the passages 82 and 84 into the combustion chamber 88 by the plunger I! when the latter is brought raised position by means of a coil spring 35 en- I circling the plunger and the upper portion of the injector cylinder [2. The spring 35 is seated at its lower end upon the flange 22 and has its upper'end in contact with a mushroom spring seat 36 secured to the end of the plunger. The

plunger l3 may be provided with an integral flange 31 adapted to slide in a cylindrical socket 38 co-axial with the bore I4 of the injector cylinder l2. An annular stop-ring 39 is screwthreaded into the upper end of the socket 38 and is adapted to engage the flange 31 for limiting the upward movement of the plunger.

The mechanism foractuating the plunger l3 comprisesa rocker arm 40 of conventional construction journaled intermediate its ends upon a shaft 4| carried by a suitable support 42 mounted upon the cylinder head 1. The rocker arm is actuated by a push-rod 43 in operative engagement with a tappet 44 having a tappet roller 45 which is adapted to ride upon the surface of a cam 46.

In four-cycle engines, as illustrated in Figure 1, the cam 46 may be mounted upon the conventional cam shaft employed for actuating the air intake and exhaust valves. However, in twocycle engines not employing tappet valves, 9. special cam shaft must be provided. Thecam 46 has three operating surfaces 41, 48 and 49. The surface 41, which embraces an arc of substantially 170 degrees contacts the roller 45 during the exhaust and suction strokes of the engine 48, which embraces an arc of substantially 90 degrees; contacts the roller 45 during the compression stroke of the piston, thus causing the push-rod 43 to be raised and'to move the plunger l3 downwardly a distance sufficient to dover the passage 28, thus sealing off-the fuel inlet to the injector chamber l1 during.compression. The surface 49 embraces an arc of substantially 100 degrees and contacts the roller 45 during the expansion stroke of the piston, thereby raising the roller still farther at the end of the compression stroke which causes the plunger iii to be forced downwardly against its conical seat in the bottom of the cup l6 to expel the fuel oil through the openings 82 and 34 into the combustion chamber of the engine cylinder.

More specifically, the operation of my fuel injecting device is asfollows:

In Figure 1, the arrow indicating a clockwise rotation refers to the direction of rotation of the crank shaft of a four-cycle engine. The arrow indicating a counter-clockwise rotation has reference to the direction of rotation of the cam shaft and the cam 46. When the cam 46 is in the position as shown in the drawing, the plunger I3 is in its raised position and the piston 6 is at the top dead center ready to begin the suction stroke. As soon as the engine crank shaft has advanced from 5 to 7 degrees, the metering pump 5|, driven through the connection 58 in timed relation with respect to the cam 46, starts to force fuel oil through the conduit passages 24, 25 and 26, past the check valve 29, into the bore 21, through passage 28, into the injector chamber l1. Since the injection of fuel oil into the injector chamber piston and permits the plunger I 8 to remain in its uppermost or raised position. The surface aooaeso come the combined resistance of the feed line and the check valve 29.

elled approximately 45 degrees past bottom dead center, the maximum lift of'the cam surface 48 will have been achieved and the plunger 13 will have moved downwardly a distance suflicient to overlap the passage 28 leading into the injector chamber I'l. Thus, the injector .chamber containing the metered 'charge'of fuel oil is cornpletely sealed against compression loss during the remainder of the compression stroke. Also, during the remainder of the compressionstroke, the compressed air in'the engine cylinder, rising in ,temperature. as the compression increases, en-

ters'the injector chamber I1 through the pas-- sages 32 and 34 and mixes with the charge of oil contained therein, however, as isobvious this compressed air is prevented from entering bore 21 due to passage 28 being closed by plunger 13 and mixing with the fuel oil contained therein. It is thus seen that while the fuel oil in chamber l1 ismixed with air, the bore 21 and passage 2d are alwaysmaintained full of fuel oil so that upon each injection strokeof pump 5| a uniform predetermined amount of fuel oil is discharged into chamber l1 which eliminates waste. in fuel and the forming ofcarbon and thereby contributes .to the smooth, economical and reliable operation of the motor.

When the lston 6 has reached top dead center at the end the compression stroke, the cam roller 45 engages the abrupt contour of the cam surface which substantially instantaneously forces the plunger l3 down against its seat at the bottom of the cup l6 to completely inject the oil charge throughthe restricted openings 32 and '34 into the combustion chamber of the engine cylinder where it is immediately ignited. It will thus be seen that while the' fuel oil is delivered to the fuel chamber I] froma low pressure source of fuel supply, the fuel is injected into the combustion chamber of the engine under high pressure by a very simple mechanism, and under a principle of operation that comes very close to air injection principle clue to the mixing of the air with the fuel while in the fuel chamber I! with the result that substantially completecombustion is obtained. The roller 45 remains in engagement with the cam surface .49 to maintain the'plunger l3 seated against the bottom of the cup l6 during the entire expansion stroke which insures complete burning of the oil charge and also prevents any exhaust gases from entering the injection chamber l1.

At the end of the expansion stroke and during the exhaust stroke,the roller 45 is gradually lowered by the sloping, trailing end of the cam surface 49 on to the cam surface 41 which per-- mits the plunger iii to be raised ,to its normal position by the action of the spring 35.

The simplicity of my fuel injecting system renders it readily responsive to timing control; From the above description it is apparent that timing control may be effected by advancing or retarding the cam 46 with respect to the crank shaft of the engine, which may be accomplished by conventional mea is well known in the art.

Although I have shown and described a specific fuel injecting device, it is to be understood that the same is for the purpose of-illustration and that changes and modifications may. be made by those skilled in the art without departing from the spirit and scope of the appended claim.

. What I claim is: a

A fuel injecting system for an oil-burning engine having a cylinder anda piston operable therein comprising an injector cylindera'rranged .in a vertical plane above the engine cylinder, a

discharge opening in the lower end'of said injector cylinderin direct communication with the combustion chamber of the engine, a plunger operable in said injector cylinder, means for normally maintaining said plunger in a retracted position during the suctionstroke of said piston, said injector cylinder having a fuel inlet passage in its side wall communicating with the chamber thereof adjacent the lower end of the plu'ng-' er when the latter is in said retracted position adapted to be covered and uncovered by said plunger, means for injecting fuel through said passage into said injector cylinder. during the suction stroke of said piston, and means for advancing said plunger including a cam, said can having a primary surface adapted to advance said plunger a-distance sufficient to cover said inlet passage during the compression stroke of said piston and a secondary surface adapted to fully advance said plunger at the end of the compression stroke of said piston to eject the fuel from said injector cylinder through said opening into the combustion chamber of the engine, said secondary cam surface maintaining said plunger fully' advanced during the expansion stroke'of said piston.

HENRY POKORNEY. 

